Steelblue and Autodesk recently introduced the largest ever 3D printed model of the San Francisco skyline, 3D printed on two Objet500 Connex Multi-material 3D Printers by Stratasys. Projecting the planned skyline in 2017, the model covers 115 square blocks of the downtown area and features nine towers in various states of development.

The 3D printed model features iconic elements such as the Bay Bridge and AT&T Park

The 6 by 6 foot model showcases much of the Financial Transbay and Rincon Hill Districts, and features the Transbay Transit Center, the new wing of the San Francisco Museum of Modern Art, AT&T Park, and the Ferry Building. The project was commissioned by Tishman Speyer and was produced by Steelblue at Autodesk’s Pier 9 facility from a digital model created by the Steelblue team.

The city model was 3D printed at 1:1250 scale at a level of detail of 30 micron, or just over 1 foot in real life. The project was 3D printed in parts so that changes to buildings can be swapped out without reprinting the entire model. Printing production took two months to complete; each city block took 6 to 18 hours to print depending on size and complexity.

We spoke with O’Brien Chalmers, president of Steelblue, for more insight on the project:

Stratasys Blog: How did you decide which scale to use for the buildings?

Chalmers: The story of this part of the city and how the model was intended to be used defined the scale. We wanted to include certain landmarks such as the Ferry Terminal and the Caltrain to represent connection to the larger Bay Area, which defined our boundary. The size of the model was based on how it would be used (number of people that would stand around it, constraints of the space, etc). There were other factors we considered such as the height of the tallest buildings and the size of the Objet500 Connex 3D Printer print bed, but the scale was a byproduct of size and story-telling decisions.

Stratasys Blog: How much of the project was generated from existing architectural renderings and how much was designed anew?

Chalmers: We rebuilt our entire digital model for the purpose of this project. We took into consideration the size that we were 3D printing to ensure the maximum amount of detail while maintaining structural integrity.

Stratasys Blog: The flexibility to swap out city blocks brings a rapid prototyping angle to civic planning. Is this a unique advantage of 3D printing? Are there other advantages that 3D printing offers over the hand-built paper models traditionally used?

Chalmers: Swapping out buildings could be done with other methods of modeling though I believe 3D printing makes it easier. The accuracy that the 3D printing provides is unique so that our ‘puzzle pieces’ will fit perfectly every time. Being able to generate detailed buildings quickly gives 3D printing an advantage. Another advantage is replication. We have 3D printed the city model more than once and at different scales with different materials.

A subsection of the model was 3D printed in transparent resin – when combined with a projection table, the model can be lit from below with guides to the street names, buildings and traffic patterns

Stratasys Blog: We noticed that a second smaller model was also created using Stratasys transparent 3d printing material.

Chalmers: Yes, we have included a photo that shows a portion of our city model 3D printed in transparent 3D printing material (VeroClear) at 1:2500 scale. The sides were frosted to maintain their form, but the streets were left clear to let light shine through from below.

Stratasys Blog: How did you decide which 3D printing materials to use for which models?

Chalmers: The initial model was 3D printed with white rigid opaque 3D printing material (VeroWhite) so that we could project data and imagery on to the surface giving the city model more life. Demographics, zoning data, traffic patterns, locations of hotels and parks, and shadow studies are all able to be highlighted on the opaque material using a projector. The rigid white model was 3D printed to live on top of a screen, so this data is projected from below instead of from above.

Stratasys Blog: Were there specific advantages or reasons you chose to use the Objet500 Connex Multi-material 3D Printer for this project?

Chalmers: The speed, level of detail possible and 3D print bed size. We are using Objet30 Pro 3D Printers currently for other projects, which still gives us the great level of detail, but with less throughput than the Objet500 Connex.

The San Francisco skyline model is one of several city models being 3D printed by Steelblue. Past projects include Midtown Manhattan and portions of Boston.